Heartbeat

.heartbeat {
  animation: heartbeat 0.6s ease-out both;
}

@keyframes heartbeat {
  0% {
    transform: scale(1);
  }
  25% {
    transform: scale(1.1);
  }
  50% {
    transform: scale(1);
  }
  75% {
    transform: scale(0.9);
  }
  100% {
    transform: scale(1);
  }
}